The present invention generally relates to an adverse condition detector that includes a sensor for detecting an adverse condition in a building. More specifically, the present invention is directed to a method and apparatus for providing an enhanced visual alarm signal such that the user can more quickly and easily determine what type of adverse condition is being sensed by the adverse condition detector.
Alarm systems that detect dangerous conditions in a home or business, such as the presence of smoke, carbon dioxide or other hazardous elements, are extensively used to prevent death or injury. In recent years, it has been the practice to develop adverse condition detectors that detect more than one type of adverse condition within a single unit. For example, detectors are currently available that include multiple sensors, such as a CO sensor and a smoke sensor, such that if either of these adverse conditions is detected, the single adverse condition detector can generate an audible alarm signal to the user indicating the type of adverse condition being detected.
Presently, combination adverse condition detectors that sense both the presence of CO and smoke emit different audible alarms depending upon the type of adverse condition being detected. The smoke alarm audible signal is defined by Underwriters Laboratory and is referred to as the Universal Evacuation Signal. The Universal Evaluation Signal has three moderate length tones separate by two moderate length pauses and a third longer pause, with the entire process repeating every four seconds.
In contrast, the CO temporal audible signal defined by UL includes four very rapid pulses occurring in less than one second with a pause of about five seconds until the next sequence of pulses. Thus, the two audible signals can be distinguished by a user that is aware of the different sounds for each of the audible alarm signals. However, a limitation exists in that the user of the adverse condition detector must know and be able to distinguish the two types of audible alarms generated by the single adverse condition detector.
Since many users only hear the two different audible patterns during a manual test of the detector, these users are unable to remember and distinguish the two different audible alarm patterns during an alarm situation. Thus, many manufacturers have determined that the use of a visual signal in addition to the audible alarm signal is an effective manner to communicate to the user the type of alarm signal being generated by a single multi-sensor adverse condition detector.
One example of a combination alarm having differing visual signals is the BRK Model No. SC01SCL. In this product, a red LED is simultaneously flashed with the smoke alarm signal to indicate to the user that the device is sensing smoke. The red LED is positioned behind a red plastic lens that in turn is positioned behind a cutout in the detector housing that resembles a flame. Thus, the user is led to associate the smoke audible alarm signal with the flashing of the red LED behind the flame cutout. Similarly, the device uses another separate red LED positioned behind a triangle-shaped cutout that simulates the shape of a molecule of gas. The second red LED is flashed along with the generation of the CO alarm signal such that the user can visually associate the flashing of the red LED behind the molecule cutout as a CO sensing.
Various other manufacturers have used different color LEDs to indicate the two types of alarm conditions being sensed. Although the two types of LEDs for the two types of adverse conditions being sensed provide a reliable technique to differentiate the two types of alarm signals, the LEDs are typically positioned within a cutout that must be visually examined by the user to determine what type of signal is being generated. Therefore, if the alarm signals are being generated in a dark building, it is difficult for the user to immediately associate the visual signal being generated with one of the types of adverse conditions being sensed.
Yet another manufacturer has developed a combination alarm that includes a single red LED that flashes when either the CO audible temporal signal or the audible smoke temporal signal is being generated. The red LED flashes simultaneously with the horn activation. In addition to the single flashing LED, the alarm utilizes a voice announcement during the sound between the horn pulses to differentiate the type of signal. For example, in a smoke event, the alarm tone sounds and the message “Fire! Fire!” is relayed. Likewise, in a CO event, the alarm tone sounds and a user hears the warning “Warning! Carbon Monoxide”. Although this type of alarm system works well with a user that understands English, a non-English speaking user would be unable to distinguish the types of alarms being generated.
Therefore, a need exists for an improved method of alerting a user of an adverse condition detector of the type of adverse condition being detected by the detector during an alarm condition. Specifically, a need exists for an adverse condition detector that generates a visual signal that allows the user to immediately associate the visual signal with the type of adverse condition being detected.